Shipping container and method of manufacture thereof



Aug. 23, 1966 M. J. M. COPPENS 3 268,109

SHIPPING CONTAINER AND METHOD OF MANUFACTURE THEREOF Original Filed July 5, 1963 I I In [:13

INVENTOR.

United States Patent 3,268,109 SI'HPPING CONTAINER AND METHOD OF MANUFACTURE THEREOF Mattheus Johannes Martians Coppens, Delft, Netherlands, assignor to Inland Steel Company, Chicago, Ill., a corporation of Delaware Original application July 5, 1963, Ser. No. 293,071. Divided and this application July 12, 1965, Ser. No.

4 Claims. (Cl. 220-72) The present application is a divisional application based upon my copend-ing U.S. application Serial No. 293,071, filed July 5, 1963, for Shipping Container and Method of Manufacture Thereof, now abandoned, which copending application is assigned to the assignee of the present application.

The present invention relates to shipping containers and, more particularly, to an improved sidewall construction for containers of the type commonly used in transporting and storing oil products, and other liquid, semi-liquid, pulverized, or granular substances. In its principal aspects, the invention is concerned with an improved sidewall construction which is characterized by its high resistance to loads, shocks and similar forces which tend to deform or otherwise damage the containers during transportation or storage.

For a number of years there has been a persistent and increasing demand for a sturdy, light-weight shipping container which is not only capable of withstanding the rigors of transportation from the supplier to the consumer, but which is also more resistant to deformation forces during periods of storage and use. In an effort to meet the foregoing dem'and, there has been a recent trend by manufacturers towards the use of thinner and lighter sheet metal in the construction of both the sidewalls and the drum heads, thus minimizing the amount and weight of materials used and, therefore, both the manufacturing and transportation cos-ts.

Let it be assumed that a SS-gallon drum is required by a consumer for use in a specified application, or range of applications. Such a drum, in order to meet the requirements of the consumer, must have or exceed minimum acceptable standards of strength which, merely by way of example, heretofore required the use of 18-gauge sheet steel. However, manufacturers have, consistent with the recent trend, attempted to make such drums of ZZ-gauge, or even 24-gauge, sheet steel rather than the heavier 18- gauge material, while at the same time providing drums which meet or exceed the consumers minimum acceptable standards of strength and which are, therefore, strong enough to be suitable for use in the same applications as drums made of the heavier gauge material.

As used herein, the term strong enough is intended to connote a drum characterized by its ability to withstand the rigors of transportation under very unfavorable conditions during one trip without developing a leak. The drum may be deformed, but the construction should be such that those deformations that are caused by the kinds of mistreatment of filled drums usually encountered during transportation do not promote the creation of sharp Wrinkles or folds, since these often rapidly develop into leaks. On the other hand, when deformations are caused they should preferably be of such a nature that it is extremely difficult (and thus more expensive than is economically justified in relation to the cost of new drums) to recondition the damaged drum by ironing out the wrinkles. The reason for this is that reconditioned drums of light-weight material always form a certain hazard from the point of view of leakage during the next trip or following trips.

The recent trend towards the use of thinner and lighter sheet material in the construction of drums has, however,

simply magnified the problems of deformation, rupture, and attendant leakage or spoilage of the contents of such drums, since such thin gauge material has not heretofore proven suitable for withstanding deformation forces of the type commonly encountered during handling, transportation and storage.

Indeed, it has been found to be very difficult to find a satisfactory compromise between the various requirements that drums must meet to conform to acceptable standards-requirements that are generally conflicting in nature in that the drums must not only be characterized by their strength, but also must be made of material which, in itself, is not as strong as that heretofore used. For example, it would serve no useful purpose to provide a light-weight drum which has a great resistance to axial forces but which collapses under a small radial load. Conversely, a drum which is highly resistant to radial loads but which collapses under small axial forces is not satisfactory. Moreover, a satisfactory drum must also possess characteristics of resistance to forces caused by oblique drops where the drum hits the ground with part of its chime. Even a drum which has suflicient strength, and what might be termed balanced strength, in all the foregoing respects would not be satisfactory if it could not stand being rolled over a reasonable distance.

With the above considerations in mind, the container industry has devised and adopted a great number of tests of different nature for the purpose of evaluating various drum constructions with regard to both the foregoing and other requirements. Such tests are primarily intended to simulate those various types of unfavorable conditions normally encountered during handling, transportation, and storage of drums in the field.

Accordingly, it is a general aim of the present invention to provide an improved shipping container construction which not only permits the use of relatively thin light-weight sheet material as compared with the relatively thicker and heavier material heretofore required, but wherein the container is characterized by its strength and resistance to deformation forces of the type normally encountered in handling, transportation and storage. While not so limited in its application, the invention will find especially advantageous use in connection with metal containers made, for example, of 22-gauge or 24-gauge sheet steel, th-us insuring saving in both manufacturing costs and dead weight.

Another object of the invention is to provide a lightweight sheet metal drum which, when subjected to the conventional performance tests adopted by the container industry, exhibits optimum performance characteristics. A related object of the invention is the provision of an improved drum construction which, because of its performance characteristics when subjected to unfavorable conditions, results in a drum characterized by its versatility and reliability in use.

In another of its important aspects, it is an object of the invention to provide an improved shaped sidewall construction for shipping containers wherein the internal axial strains created in the sheet material as an incident to shaping the latter during the sidewall forming operation are minimized, thus providing a stronger drum construction. As a consequence of attaining the foregoing objective, a drum sidewall embodying the invention permits of greater deformation, or strain, in the field before failure than has heretofore been possible.

Other objects and advantages of the invention will become apparent as the following description proceeds, taken in conjunction with the accompanying drawing, in which:

FIGURE 1 is a side elevation of a shipping container embodying the features of the present invention; and,

FIG. 2 is an enlarged, fragmentary, longitudinal section of a portion of the sidewall of the container shown in FIG. 1, and illustrating also details of the exemplary chime construction used for connecting an end member, or drum head, to the sidewall.

While the invention is susceptible of various modifications and alternative forms, a specific embodiment thereof has been shown by way of example in the drawings and will herein be described in detail. It should "be understood, however, that it is not intended to limit the invention to the particular form disclosed, but, on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as expressed in the appended claims.

Referring now to the drawing, there is illustrated in FIG. 1, an exemplary shipping container or drum having a generally cylindrical body or sidewall 11. In the illustrative form of the invention, the opposite ends of the drum are closed by a pair of disc shaped end members 12 which are respectively secured to the opposite extremities of the sidewall 11 by a curled seam or chime 14.

In order to enhance the characteristics of drum strength and resistance to deformation forces, provision is made in the illustrative drum construction for concentrating the metal in the vicinity of the chime 14, thus substantially reinforcing the drum and permitting the latter to be tipped on its edge and rolled on the chime so as to facilitate movement thereof. To this end, and as best illustrated by reference to FIG. 2, the chime 14 is defined by adjacent layers or plies of the sidewall 11, the drum head or end 12, and an annular metallic reinforcing ring 15. As here shown, the exemplary chime is comprised of eight plies-there being two plies 11a, 11b of sidewall material 11, three plies 12a, 12b, 120 of end material 12, and three plies 15a, 15b, 150 of reinforcing ring material 15.

In formation of the eight-ply chime 14, for example, by bending, turning, rolling or similar manufacturing procedures well known to those skilled in the art, the outermost extremities of the reinforcing ring 15 and end 12 are bent or turned over into a substantially U-shaped configuration encompassing the extremity of the sidewall 11. The entire connection, including the extremity of the sidewall 11, is then bent or turned over again into a second substantially U-shaped configuration. Thus, the marginal edge of the sidewall is bent once through an angle of 180 into a U-shape whereas the marginal edges of the ring 15 and end 12 are bent twice through angles of 180 into a double U-shape. In the exemplary chime therefore, the

inner ply 15a of the ring 15 abuts the inner ply 12a of the end, while the outer ply 15b of the ring abuts the outer ply 12b of the end. The intermediate ply 15c of the ring is received between the inner ply 11a of the sidewall 11 and the intermediate ply 120 of the end, while the outer ply 11b of the sidewall is accommodated between the intermediate and outer plies of the end 12. Thus, the plies 11a, 12a, 15a, 11b, 12b and 15b define an inverted U- shaped configuration, while the plies 12b, 15b, 12c and 150 define a U-shaped configuration.

The provision of an eight-ply chime with containers constructed in accordance with the invention has various advantages. For example, the connections between the sidewall 11 and the ends 12 are reinforced, thus minimizing the danger of deformation of the chime and separation of the end and sidewall. At the same time, the radial thickness of the chime is increased, particularly where the wall thickness of the ring 15 is greater than that of the sidewall 11, as shown in the exemplary construction of FIG. 2. Such an increase in overall thickness of the chime materially reduces the risk of -a chime cutting into the sidewall of an adjacent drum where the drums are shipped so that their longitudinal axes are other than parallel, for example, where their axes are perpendicular to one another.

The drum 10 (FIG. 1) may, in a conventional manner, be provided with a suitable filling and discharge opening and a vent hole. Such openings may conveniently be formed in one end member 12 and closed by means of separable bungs, plugs, screw caps, or similar closure devices, here shown generally at 16 and 18.

In accordance with one of the important aspects of the present invention, the drum body or sidewall 11 is formed over substantially its entire length with a multiplicity of radially outwardly extending peripheral beads separated by a plurality of radially inwardly extending peripheral furrows, with the alternate beads and furrows being so interrelated and associated with one another as to form a container sidewall construction which exhibits optimum performance characteristics in terms of balanced strength and resistance to deformation forces. In the exemplary sidewall construction shown in FIG. 1, twenty-six such beads 19 are formed in the sidewall 11, the beads being respectively spaced apart by twenty-five furrows 20.

Of course, while twenty-six beads 19 and twenty-five furrows 20 have been shown, it will be understood that the particular number of beads and furrows may vary without departing from the invention. It is important, however, that the beads and furrows be interrelated and associated with one another in accordance with particular criteria that I have discovered and which are set forth herein'below. However, 'by way of example, when a 55- gallon drum is manufactured in accordance with these criteria, it will generally include from twenty-three to twenty-seven beads alternating with twenty-two to twentysiX furrows, assuming, of course, that the drum is of generally standard overall dimensions; i.e., on the order of approximately thirty-two inches in height (as measured from end member to end member) and formed from a cylindrical blank having an inside diameter of approximately twenty-two and one half inches.

As best illustrated by reference to FIG. 2, the top portion of each of the beads 19 and the bottom portion of each of the furrows 20 have a smoothly curved radial cross-section, and respective ones of the flanks of each bead blend smoothly into a flank of each of the adjacent furrows. In the preferred form of the invention shown in FIG. 2, the radial cross-section of each head 19 and of each furrow 20 comprise circular arcs which blend directly into one another. I have discovered that advantageous results are obtained in terms of balanced strength where the ratio of the radius r of the bead arcs are on the order of 0.4 to 1.0, and preferably 0.6, times the radius R of the furrow arcs.

In the preferred form of the invention, the included angle on between the radial tangent to the flank of each head 19 (at the point where the bead flank blends into the flank of an adjacent furrow 20) and the longitudinal axis of the sidewall 11 is on the order of 35". I have discovered that advantageous results can be obtained, again in terms of balanced strength, if the angle a lies within the range of 20 to 50.

I have further discovered that the ratio between the height of the beads 19 (or the depth of the furrows 20) and the axial distance between the centers of the tops of the beads (or between the centers of the bottoms of the furrows) plays a par-t in obtaining the optimum correspondence of axial strength to radial strength of the drumthis ratio preferably being on the order of 0.25. That is, the beads and furrows serve to increase the resistance of the sidewall 11 .to radial loads, while reducing the resistance thereof to axial loads. Thus, when provided with deeper beads 19, the sidewall will be stronger radially, but weaker axially. Conversely, with shallower beads, the sidewall will be weaker radially and stronger axially. I have found that advantageous results are obtained in terms of balanced strength if the diiference between the smaller diameter of the sidewall, as measured at the bottom of the furrows 20, and the larger diameter of the sidewall, as measured over the top of the beads 15,

lies in the region from 0.4 to 0.6 times the axial distance between the centers of the tops of adjacent beads.

While those skilled in the art will appreciate that the present invention is not limited to containers having particular given capacities, it has been found, by way of example, that very satisfactory results are attained with 55-gallon drums made in accordance with the invention wherein the sidewall 11 is formed with twenty-three to twenty-seven beads 19 alternating with twenty-two to twenty-six furrows 20; the outside diameters of the drum are approximately 22 inches as measured at the bottom of the furrows 20, and approximately 23 /2 inches as measured at the tops of the beads; the outside diameter of the chime 14 is on the order of approximately 22% inches; the axial distance between the tops of adjacent beads is on the order of 1 inches; and the axial distance between the ends 12 of the drum is approximately 31 5 inches. Additionally, the radius r of curvature of the beads 19 is on the order of of an inch, while the radius R of curvature of the furrows 20 is on the order of /2 inch.

In carrying out the present invention, provision is made for minimizing the danger of deformation and failure of the vulnerable chime assemblies as an incident to rolling of the drum. Such drum failures have heretofore been particularly prevalent in the vicinity of the chime 14 when the drum is rolled along the ground or other uneven surfaces. To accomplish this, the chime 14 is offset radially inward with respect to the tops of the beads 19, and, in the preferred form of the invention as shown in FIG. 2, also with respect to the outside diameter as measured at the bottoms of the furrows 20. The arrangement is such that when a drum 10 is rolled along on its sidewall 11, the relatively vulnerable chimes 14 are kept clear of the surface on which the drum is being rolled. For example, in the exemplary SS-gallon drum described above, the chimes are kept free of the ground since the outside diameter of the chime 14 (approximately 22% inches) is less than the outside diameter of the beads 19 (approximately 23 /2 inches). Moreover, even greater protection for the chimes is insured where the outside diameter thereof is slightly less than the outside diameter of the furrows 20 (e.g., less than 22 inch outside diameter of the furrows in exemplary SS-gallon drum), since in this instance the chi-mes 1-4 are kept free of the ground even when the beads 19 collapse because of excessive loads which may occur, for example, when a filled drum is rolled along an uneven surface.

It will be appreciated by those skilled in the art that a given piece of sheet metal is capable of only a certain percent of elongation or strain before failure occurs. A certain amount of the permissible elongation will, of necessity, occur during the sidewall shaping operation. For example, in the formation of drums in accordance with the invention, a substantially cylindrical metal blank is shaped by forming alternating beads and furrows therein. The beads and furrows may be formed in various Ways, such as rolling, locally expanding, or locally shrinking the blank. These operations will, of course, change the circumferential dimension of the blank at axially spaced points, thus circumferentially straining the blank. At the same time, some axial elongation or strain is also created in the sidewall due to elongation of the blank material.

I have found that in carrying out the present invention, the drum sidewall is preferably formed by a shaping operation wherein the blank material on both sides of each bead is permitted to move towards the bead as the latter is formed. This permits the formation of a sidewall 11 embodying the invention wherein the strains in the formed sidewall are primarily limited to circumferential strains, while axial strains are substantially minimized in the finished sidewall. Consequently, the finished drum 10 is capable of absorbing greater punishment in the field than would otherwise be possible since the sidewall m-aterial is capable of greater longitudinal or axial elongation in the field before it will fail.

To this end, when the beads 19 (or furrows 20) are formed in the blank one at a time, the opposite extremities of the blank are maintained free of axial constraint, thus permitting the blank material on each side of the bead (or furrow) being formed to move axially towards the head (or furrow). Alternatively, in those instances where two or more beads are formed simultaneously, for example, by the use of internal expansible die members, the die members are preferably mounted .to move axially towards one another during the expanding operation, thus permitting the blank material at both sides of each bead being formed to move towards the bead. Similarly, two or more of the beads may be formed simultaneously by the use of an inflatable and deflartable bag mounted within external die members, the blank being placed between the bag and the dies and the dies being permitted to move axially towards one another. This latter type of equipment is described in greater detail in the copending application of Oscar J. Van Leer and Christian Ragettli, Serial No. 850,247, filed November 2, 1959, now Patent No. 3,099,311.

Tests have demonstrated that where a shaped sidewall similar to that shown in FIGS. 1 and 2 was formed by methods which inhibited axial movement of the blank material on both sides of the head during the shaping operation, the axial distance between two points on the uniformed blank remained the same as the axial distance between the same two points (chosen, for example, to coincide with the tops of two adjacent beads) on the finished sidewall section. At the same time, the distance between the two points as measured along the surface of the shell increased. By way of example, a finished sidewall section which measured 1.25 inches from the top of one head to the top of the adjacent bead (and hence, 1.25 inches between the same two points on the unformed blank), measured 1.512 inches along the surface of the sidewall. Therefore, the average net axial strain or elongation of the blank Was on the order of 21 However, tests have also demonstrated that when a sidewall having the same finished shape and made of the same material is formed by methods which permit axial movement of the blank material on either side of the bead, the axial elongation of the material can be limited by controlling the relationship between the radial ex pansion and axial contraction of the forming dies. By way of example, a finished sidewall section which measured 1.25 inches in an axial direction from the top of one head to the top of the adjacent bead, and 1.512 inches along the shell surface .between the same two points (i.e., both dimensions being identical to the corresponding dimensions set forth above where axial movement of the blank material was inhibited), the original axial length of the unformed section was 1.484 inches. That is, the beads moved axially toward one another by .234 inch during the forming operation. In this case, the average net axial strain was on the order of 2%, a substantial reduction over the 21% average net axial strain encountered where no axial movement of the blank is permitted.

I have found that advantageous results in terms of balanced strength can be achieved where the relationship between radial expansion and axial contraction is controlled so that the average net axial strain of the sidewall material as measured from top to bottom of the shell is on the order of 2%, and preferably does not exceed 5%. As used herein, and in the appended claims, the term axial strain is intended to connote the strain as measured longitudinally along the sidewall 11, it being understood that elongation measured in the finished product is not purely axial in view of the undulating nature of the sidewall. Moreover, while the illustrative container shown in FIG. 1 has been illustrated as having twenty-six beads 19 spaced apart by twenty-five furrows 20, it will be understood that either more or less beads and furrows could be provided. However, I have found that the advantageous results of the present invention are achieved only where there are at least three, and

preferably more, beads 19. Therefore, in the appended claims the invention has been defined in terms of a container sidewall and method of manufacture thereof, wherein the sidewall is provided with a multiplicity of beads and it is intended that the term multiplicity connote at least three beads.

In keeping with the present invention, the drum 10 is preferably formed from a cylindrical blank having a diameter smaller than the diameter of the shaped sidewall as measured at the bottom of the furrows, thus permitting the unformed extremities of the sidewall to be formed into a chime 14 having an external diameter which is smaller than the external furrow diameter.

I claim as my invention:

1. A sidewall for use with a generally cylindrical sheet metal shipping container of the type having a pair of end members respectively connected to the opposite extremities of the sidewall, said sidewall having a multiplicity of radially outwardly extending peripheral beads spaced axially from one another with the spacing between adjacent beads defining a plurality of radially inwardly extending peripheral furrows, the top portion of each of said beads and the bottom portion of the adjacent furrows defining a smoothly curved radial cross section, the respective flanks of each of said beads blending smoothly into a flank of each of the adjacent furrows, said sidewall having an average net axial strain as measured from top to bottom thereof of about 2% 2. A sidewall for use with a generally cylindrical sheet metal shipping container of the type having a pair of end members respectively connected to the opposite extremities of the sidewall, said sidewall having a multiplicity of three or more radially outwardly extending peripheral beads spaced axially from one another with the spacing between adjacent beads defining a plurality of radially inwardly extending peripheral furrows, the top portion of each of said beads and the bottom portion of the adjacent furrows defining a smoothly curved radial cross section, the respective flanks of each of said beads blending smoothly into a flank of each of the adjacent furrows, said sidewall having an average net axial strain as measured from top to bottom thereof less than 3. The method of making a shaped-metal sidewall for a sheet metal container comprising the steps of forming a substantially cylindrical blank of sheet metal, locally expanding said blank in a radial direction at a multiplicity of axially spaced points to form a series of three or more radially outwardly extending peripheral beads alternating with radially inwardly extending peripheral furrows while permitting the blank material at both sides of each bead being formed to move towards said head, stopping said expanding operation when said blank is formed with alternating beads and furrows over substantially its entire length with the exception of the marginal edges at the extremities of the blank, and controlling the relationship between radial expansion and axial contraction of the blank so that the average net axial strain of the sidewall as measured from top to bottom thereof is on the order of 2% 4. The method of making a shaped metal sidewall for a sheet metal container comprising the steps of forming a substantially cylindrical blank of sheet metal, 10- cally expanding said blank in a radial direction at a multiplicity of axially spaced points to form a series of at least three radially outwardly extending peripheral beads alternating with radially inwardly extending peripheral furrows while permitting the blank material at both sides of each bead being formed to move towards said bead, stopping said expanding operation when said blank is formed with alternating beads and furrows over substantially its entire length with the exception of the marginal edges at the extremities of the blank, and controlling the relationship between radial expansion and axial contraction of the blank so that the average net axial strain of the sidewall as measured from top to bottom thereof is less than 5%.

References Cited by the Examiner UNITED STATES PATENTS 1,200,748 10/1916 Munger 22072 1,825,030 9/1931 Vaughn 113-120 1,886,803 11/1932 Giesler 113120 FOREIGN PATENTS 129,753 11/ 1927 Switzerland.

THERON E. CONDON, Primary Examiner.

G. T. HALL, Assistant Examiner. 

1. A SIDEWALL FOR USE WITH A GENERALLY CYLINDRICAL SHEET METAL SHIPPING CONTAINER OF THE TYPE HAVING A PAIR OF END MEMBERS RESPECTIVELY CONNECTED TO THE OPPOISTE EXTREMITIES OF THE SIDEWALL, SAID SIDEWALL HAVING A MULTIPLICITY OF RADIALLY OUTWARDLY EXTENDING PERIPHERAL BEADS SPACED AXIALLY FROM ONE ANOTHER WITH THE SPACING BETWEEN ADJACENT BEADS DEFINING A PLURALITY OF RADAILLY INWARDLY EXTENDING PERIPHERAL FURROWS, THE TOP PORTION OF EACH OF SAID HEADS AND THE BOTTOM PORTION OF THE ADJACENT FURROWS DEFINING A SMOOTHLY CURVED RADIAL CROSS SECTION, THE RESPECTIVE FLANKS OF EACH OF SAID BEADS BLENDING SMOOTHELY INTO A FLANK OF EACH OF THE ADJACENT FURROWS SAID SIDEWALL HAVING AN AVERAGE NET AXIAL STRAIN AS MEASURED FROM TOP TO BOTTOM THEREOF OF ABOUT 2%. 